# Investigating into the factors that affect acceleration.

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Introduction

Investigating into the factors that affect acceleration

Planning

I have chosen to investigate the affect changing the amount of force applied to an object has on acceleration.

## Hypothesis

I predict that as the amount of force applied to the trolley increases, the acceleration will increase in direct proportion. I believe this will happen because according to Newton’s Second Law, increasing the force increases the acceleration, provided the mass stays the same. Therefore, acceleration is directly proportional to the force applied.

Fair Test

Without fair testing the experiment would be useless because the information gathered would not be accurate or reliable. Here are the things we did to ensure our experiment was a fair test:

- The distance travelled; the mass and weight of the trolley shall remain constant, as these are not the factors we will be changing.
- The only thing we will change will be the force applied to the trolley. No force will be applied to the trolley when it is at the top of the runway, instead we will just let go of it and let gravity be the force.
- When putting the trolley at the top of the runway we will make sure that the back wheels of the trolley are touching the ticker timer – this way each experiment will start in the same place.
- We will test the trolley beforehand to ensure all wheels were working, because if one or more wheels are not working this could affect the speed/acceleration of the trolley.

Safety Precautions

As with all experiment, safety is crucial. Every experiment possesses some form of danger and through these guidelines I hope the risk of danger will be minimised:

- Make sure the trolley is stopped before it reaches the end of the runway where the pulley is to prevent damage to trolley, runway or pulley.

- Make sure that when catching the trolley at the opposite end of the runway you are not in front of it before it reaches a halt as it could cause an injury

Ticker Timer

For this experiment we shall use a ticker-timer to record our results. A ticker-timer is a way of analysing the motion of objects. As the trolley moves, it drags the tape through the ticker timer, thus leaving a trail of dots, which were printed there by a vibrating metal bar running on an electric current, which hits a piece of paper fifty times a second. The analysis of a ticker tape will reveal if the object is moving with constant velocity or accelerating. This is how we hope to record the acceleration of our trolley. To get the results from the ticker timer tape, you need to divide the tape into five dot strips, this is because each five dots is equal to 0.1 seconds.

## Preliminary Work

Before the actual experiment took place, we decided to do some preliminary work. There was a chance that something could go wrong, for example, the trolley could hit the side of the runway, or the weights could fall off or the ticker timer would not be entirely accurate. So we gave the experiment a test run to make sure everything worked according to plan. The test run went smoothly and so we all agreed the experiment would be a success

## Prediction Graph

## Equipment

- Runway
- Trolley
- Metre Stick
- Ticker Timer
- Roll of ticker timer tape
- Pulley
- String
- Weights

Middle

#### Force = 2N

Acceleration = (final speed – start speed) ÷ time taken

Final speed = length of last five-dot strip ÷ time taken

Time Taken = number of five dot strips x 0.1 seconds

Final speed = 11.1 ÷ 0.1

= 111 cm/s

Time taken = 12 x 0.1 seconds

= 1.2 seconds

Acceleration = (111 cm/s – 0 cm/s) = 1.2 seconds

= 92.5 cm/s

#### Force = 3N

Acceleration = (final speed – start speed) ÷ time taken

Final speed = length of last five-dot strip ÷ time taken

Time Taken = number of five dot strips x 0.1 seconds

Final Speed = 17.3 ÷ 0.1

= 173 cm/s

Time taken = 8 x 0.1 seconds

= 0.8 seconds

Acceleration = (173 cm/s – 0 cm/s) ÷ 0.8 seconds

= 216.25 cm/s

#### Force = 5N

Acceleration = (final speed – start speed) ÷ time taken

Final speed = length of last five-dot strip ÷ time taken

Time Taken = number of five dot strips x 0.1 seconds

Final speed = 19.5 ÷ 0.1

= 195 cm/s

Time taken = 6 x 0.1 seconds

= 0.6 seconds

Acceleration = (195 cm/s – 0 cm/s) ÷ 0.6 seconds

= 325 cm/s

#### Force = 6N

Acceleration = (final speed – start speed) ÷ time taken

Final speed = length of last five-dot strip ÷ time taken

Time Taken = number of five dot strips x 0.1 seconds

Final speed = 19.9 ÷0.1

= 199 cm/s

Time taken = 5 x 0.1 seconds

= 0.5 seconds

Acceleration = (199 cm/s – 0 cm/s) ÷ 0.5 seconds

= 398 cm/s

#### Force = 7N

Acceleration = (final speed – start speed) ÷ time taken

Final speed = length of last five-dot strip ÷ time taken

Time Taken = number of five dot strips x 0.1 seconds

Final speed = 22 ÷ 0.1

= 220 cm/s

Time taken = 6 x 0.1 seconds

= 0.6 seconds

Acceleration = (220 cm/s – 0 cm/s) ÷ 0.6 seconds

=366 cm/s

#### Force = 8N

Acceleration = (final speed – start speed) ÷ time taken

Final speed = length of last five-dot strip ÷ time taken

Conclusion

Given more time, I would have liked to repeat each experiment up to five times, to ensure the results were fair –and to prevent the amount of anomalous results. Also, if I were to do it again, I feel that we could extend the experiment. Originally the aim was to find out the factors which affected acceleration. During this experiment we only altered the force and nothing else, it would be worthwhile to alter other things such as the mass of the trolley, the distance, the weight etc. It would be interesting to see if we could prove Newton’s Second Law through other experiments using different trolleys. (His law states that acceleration is directly proportional to the force applied). For example, we have proved (to the best of our ability) that through using the trolley that we did Newton’s Second Law does not work, but would it work for other trolleys?

Abbie Taylor 10KG

This student written piece of work is one of many that can be found in our AS and A Level Mechanics & Radioactivity section.

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